Reduced Degree-of-Freedom Thermal Fluid Simulation
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Solution Overview
Problem
Thermal hydraulic simulations for incompressible fluids face long calculation times due to difficulties in setting time step intervals and high costs associated with solving thermal hydraulic equations, making it challenging to efficiently grasp heat distribution and fluid flow.
Innovation Solution
A thermal hydraulic simulation program that reduces the degrees of freedom of velocity and temperature field models using dimension transformation matrices, allowing for a second simulation with reduced models to enhance calculation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal hydraulic simulation is carried out using conventional time series simulation with Navier-Stokes equations, then solution accuracy is maintained, but calculation time becomes excessively long
Solution Approach 1:
The patent segments the thermal hydraulic simulation into two distinct phases: a preliminary simulation phase that captures essential flow patterns, and a subsequent simulation phase that uses these patterns as initial conditions. This segmentation allows the simulation to avoid recalculating established flow patterns, significantly reducing calculation time while maintaining accuracy for new thermal conditions.
Solution Approach 2:
The patent performs a preliminary simulation to establish initial flow patterns and temperature distributions before conducting the main simulation. These preliminary results serve as optimized initial conditions that accelerate convergence, eliminating the need to solve the full Navier-Stokes equations from scratch and thereby reducing overall calculation time.
2Productivity
If time step intervals are increased to reduce calculation time, then productivity improves, but solution stability deteriorates due to CFL condition restrictions
Solution Approach 1:
The patent implements dynamic time step adjustment where the time step size varies based on the simulation phase and flow conditions. During the preliminary simulation, smaller time steps ensure stability, while during subsequent simulations using established flow patterns, larger time steps can be employed without compromising stability, thus improving productivity.
Solution Approach 2:
The patent copies established flow patterns from the preliminary simulation to serve as initial conditions for subsequent simulations. This copying approach allows the use of larger time steps in subsequent simulations because the fundamental flow structure is already known, maintaining stability while improving calculation speed.
3Measurement precision
If full thermal hydraulic equations are solved at each time step to ensure accuracy, then measurement precision is maintained, but device complexity and computational cost increase
Solution Approach 1:
The patent applies partial action by solving the full thermal hydraulic equations only during the preliminary simulation phase, while using simplified approaches with established flow patterns for subsequent simulations. This partial application of the complex equations maintains accuracy where needed while reducing overall computational complexity.
Solution Approach 2:
The patent changes simulation parameters between phases: during preliminary simulation, full equation solving with detailed parameters ensures accuracy, while in subsequent simulations, the system uses simplified parameters based on established patterns, reducing computational complexity while maintaining sufficient accuracy.
Data Source
AI summary
A prior simulation of a velocity field and a temperature field is carried out, and snapshot data of the velocity field and that of the temperature field are collected during the prior simulation. Then principal component analysis on the collected snapshot data obtains velocity-field and temperature field dimension transformation matrixes, on the based on which the analysis models of the velocity field and temperature field having respective first degrees of freedom are converted into reduced degree-of-freedom models. Consequently, a simulation of the velocity field and the temperature field is carried out using models having respective reduced degrees of freedom (i.e., second degrees of freedom).